I created the following SearchComponent that wraps a deduplicate filter
around the current query and added it to last-components. It appears to
be working, but is there any way I can improve the performance? Would
this be considered and added to the filtercache? Am I even caching
correctly?

Thanks for any input/suggestions

...
  private Map<String, Filter> filtersByField = new HashMap<String,
Filter>();

   @Override
   public void prepare(ResponseBuilder rb) throws IOException {
     SolrParams params = rb.req.getParams();

     if (params.getBool(DuplicateParams.DEDUPLICATE, false)) {
       String field = params.get(DuplicateParams.DUPLICATE_FIELD);

       if (field == null) {
         throw new SolrException(SolrException.ErrorCode.BAD_REQUEST,
"Deduplicate field is required");
       }

       Filter filter = filtersByField.get(field);

       if (filter == null) {
         filter = new CachingWrapperFilter(new DuplicateFilter(field,
DuplicateFilter.KM_USE_FIRST_OCCURRENCE,
DuplicateFilter.PM_FAST_INVALIDATION));
         filtersByField.put(field, filter);
       }

       rb.getFilters().add(new FilteredQuery(rb.getQuery(), filter));
     }
   }
...